Telephone central switching system.



E. A. GRAY & E c. MOLINA. TELEPHONE CENTRAL SWITCHING SYSTEM.

APPLICATION FILED MAY17, 1907. Y Y Patented July 7, 1914.

a SHEETS-SHEET 1.

I Cir-cull.-

Office Selectdr;

J) j I p Z Con necfq rs Trunk Selector B. A. GRAY & E. '0. MOLINA.TELEPHONE CENTRAL SWITCHING SYSTEM.

APPLICATION FILED MAY 17, 1901. 1,102,907, Patented July 7, 1914, 'aSHEEN-SHEET 2.

Primary Selectors .1

Connector-s a JecandaT Seleccrs fittest.

E. A. GRAY & B. C. MOLINA.

TELEPHONE CENTRAL SWITCHING SYSTEM. APPLICATION FILED MAY 17, 1907.

g lgg gg y I Patented July ,7, 1914;.

65 WW 7* 4S2 if 0 b 7:? *MH Gffe'ce a Keys E. A. GRAY & E. G. MOLINA.TELEPHONE CENTRAL swrrcnme SYSTEM.

APPLICATION FILED MAY 17, 1907.

Patented July '7, 1914.

8 SHEETSSHBET 7.

Lwwm

Thousands- ]lundreals Controller and Translator Prima'ry Registerfltest. 6 'Inmntom'.

E. A. GRAY '& E. O. MOLINA. TELEPHONE CENTRAL swrroame SYSTEM.

APPLIOATION FILED MAY 17, 1907.

Patented July 7, 191% Keys k 99 Keys.

Tens-Unitsdontwllen 1 curtain saaa' rarest UFFKQ;

ERNESTA. GRAY, OF BOSTON, AND EDWARD C. MOLINA, OF ARLINGTON, MASSACHU-SETTS, ASSIGNORS TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A

CORPORATION OF NEW YORK.

TELEPHONE CENTRAL SWITCHING SYSTEM.

Specification of Letters Fatent.

Eatented July It, 1914.

Application filcd lllfllay 17, 1907. Serial No. 374-3291.

To all whom it may concern ,o It known that we, ERNEST A. (may andEDWARD C. lVloLiNA, residing'at Boston and Arlington, in the counties ofSufiolk 'or B-operator, depending upon whether the desired subscribersline terminates at the same or another oilice of thedistrict, tests thecalled line. If this is busy the operator so notifies the callingsubscriber and disconnects the switchcord which has been employedifromthe answering jack, or, if

r the line is idle, completes the connection,

rings the called subscriber andsupervises and finally disconnects thelines. lnautomatic systems the operator is dispensed with, except,perhaps, in toll connections,

and all the above-mentioned operations taking place at the centraloffice are performed by electromechanical apparatus controlled by amechanism situated at each substation and manipulated by the callingsubscriber. Both of these systems possess inherent diiiiculties. Inmanual practice the number of acts which the operator must perform foreach connection greatly limits the lines the calls of which she cananswer, and since a considerable percentage of these calls must betrunked to another office, the introduction of a second operator stillfurther increases the amount which must be expended in salaries and cutsdown the economy of operation. lhe efficiency of the service alsosuffers because of the added liability to error in the transfer of callsbetween the A and B operators,

and because of the assignment of trunks and n tall, that portion of thesystem including the the delay whichthis occasions. In automaticexchanges, not onl is the central otlicc apparatus comparatively costly,but the installing inthe substations of the somewhat complicated-'controlling apparatus having many spring contacts and moving partsseriouslyincreases this, while the maintenanee of these widely separatedmechanisms still further swells the expense. Then the burden ofperformin the operationseontrolling selection is t. rown upon thesubscriber, who not usually being skilled, and often laboring under thedisadvantage of poor light upon the indicating numerals of thecontroller, is liable to error, wasting his own time and that-of thepersonv wrongly called, and uselessly tying up a portion of the centralofiice equipment.

The present invention has forits principal object the revision of asystem combining the best .atures of manual and automatic practice,attaining thereby results excelling both in economy and efficiency. Thesubscriber may call as in central energy manual exchanges, by simplyremoving his receiver from its book and verbally communicating his orderto an operator. This operator has merely to connect an element of theofiee apparatus and her telephone.-

set to the calling line, receive the designw tion of the desired ofliceand number of the, subscriber to be called and register these Thereafterupon a controlling apparatus. a l connecting Ste 78 are carried out bye180? trically controlle mechanisms without further effort upon thepartof the answering. operator, who is free to make other con nections,and Without the introduction of a second or B-operator. The onlyadditional attention iven to each call consists in the disconnection ofthe calling line from the central oiiice apparatus, afterthe operatorhas been notified of the termination of the conversation by a signalfollcwing the hanging up of the receiver by the calling subscriber.

The invention consists in the various features and combinationshereinafter scribed and more particularly claimed.

In the accompanyingdrawings, Figures 1 and 2 show schematically the moreimportant apparatus at two oliicea'arranged in accordance with ourinvention. r Fig. 3 illus-" trates diagrammatically, but in greaterdecord circuit and the oiiice and trunk selec tors. Figs. 4 and 5 are smilar views of the primary'and secondary selectors and the finalselector, respectively; and Figs. 6, 7 and 8 show respectively theoflice, thousands hundreds and tens-units sections of the controller,the second pf these including the translator.

Similar characters designate like elements throughout the severalfigures.

The system will be here. considered as applied to an exchange having aplurality of central stations, and ten of these may be assumed, each ofa capacity of ten thousand lines, so that in all one hundred thousandsubscribers will be provided for.

In Figs. 1 and 2 the chief pieces of apparatus and intermediateconductors at the central stations or ofiices Afand' A p are shown, andsince hereinafter, in describing the operation of the system, A will betaken as the station through which a call is originated and A thestation completing the connection with the called subscriber, the callanswering and connection completing apparatus have been given specialprominence at stations A. and A respectively, and either omitted orbarely indicated at the other station. Moreover, in these figures forthe sake of clearness the various circuits have been represented bysingle lines, though there are provided complete metallic circuits whichmay include in port ons a third wire, as will be seen in Figs. 3 to 8,to which reference should be had for such minor mechanisms as relays andfor details of the appa-v ratus and'circuits generally.

V i'lppamtus of the connecting circuit. Of the substations but a singleone appears for each central station, these substations a and a beingprovided with the apparatus usual in central energy systems, thefirstnamed being joined by line conductors Z and t to a manuallyoperable switch. This switch may be furnished by a jack J (Fig. 3) tothe tip and ring contacts of which the line conductors lead and withwhich co- 0" crates a plug P. With the line conducand with. a thirdconductor Z connected to the sleeve contact of the jack are associatedthe wellknown line and cutofi relays it and R the former of which hastwo windings, and the line signaling lamp 0. A suitable number of theseanswering jacks v J and their corresponding line, lamps are situated ateach operators position, there being no multiple of said jacks.

The plug P furnishes one terminal of a connecting or cord circuit C, ofwhich enough are assigned to each operator to permit the caring for themaximum number of simultaneous connections. As is customary, each cordhas the main. conductors or talking leads L 1 united, respectively, toth tip' landring of the plug,-and a-third conductor L leading to thesleeve. It, includes a repeating coil obetween the h'alves ofjwhich isbridged the central station batteryli nzitlp its positive pole grounded.This battery may be common to all the conductors of the station, but torender the connection more clear others will be shown and referred to asindependent.- The cord also contains the operators listening key K andthe telephone set (1 supervisory signal lamps O and O with thesupervisory relays R and R, the latter of which is marginal, togetherwith the originating relay R controlling relay R and double wound guardrelay R. The purposes of the relays and minor elements in the cord andthroughout the system will be, made to appear more fully in the descrip'tion of operation, where mention will also be made of the manyarmatures, contacts and conductors, reference to which independentl ofthe circuits of which they are a part and the functions which theyperform would convey but little information.

Ofiice aim! trunk selecting apparzfus.-The strands L L of the cordcircuit are continued beyond the con'tactsof relay R- by main leads orconductors L and L terminating in a selecting apparatus D, whichservesin the present instance to pick out the office with whiclnconnection isdesired. Additional conductors L and L also lead between the apparatus Cand D. The office selecting apparatus includes an electromechanlcalswitch S of which there are several well-known forms available, thisbeing here shown as provided with a rotatable shaft 8 which carriesinsulated from it main contact members or arms s s and a test contactmember .3 each of these arms cooperating with'a series of stationary contacts s. The shaft also has fixed to it ratchet wheels 8 and s engagedby pawls m and m respectively, movable withthe armatures of motormagnets M and M to advance the contact arms in long and short steps overthe fixed terminalsupon the energization of said motor magnets. A spring8 exerts its tension to hold the arms normally in a position out ofcontact with an active terminal.

A pawl it, brought intoengagement with the ratchet wheel 8 by theattraction of a retaining magnet H temporarily holds the arms at thepoints to which theymay have been advanced by the motor magnets. An oii'normal contact device 8 operates to vary the circuit connections whenthe arms are stepped from their initial positions, as wilLbe hereinafterdescribed. As illustrated, both in this device and those of the otherswitches of the system, the movable contact members are raised when theadvance of the switch arms begins.

To allow the groups of trunk conductors which connect the oflice. A withothers in the district to efficiently serve the maximumnumber-ofsubscribers, all the ofiice selectors are given access to anyone of the trunks'in allgroups, and this is accomplished bv multi )l inheir ii 1d contacts to said trunks go ,.i i

But with as many oiiices as ten, which in;

this case have been assilmed as comprised within the. district, andwith, the number of trunks necessary-to satisfactorily handle the callsof each office with the maximum elliciency and economy, it may be found.that using the switches S for the direct selection of oilice trunksrequires more fixed. terminals for each switch than, is practical, bothbecause of, structural considerations and speed of selection. For thisreason we have shown associated with the otlice selectors groups oftrunk selecting, apparatus E, the arrangement, being as follows,reference being had to Fig. l. :"lhe terminals 8 of each switch S aredivided into ten successive groups 1/ corresponding to the total numberof offices. The space covered by each sub-- tends the angle throughwhich the selector arms are advanced upon each energization of. themotor mag-net M. The terminals 5 are themselves separated; by distancesequal to the. short steps produced by the magnet M Similar contacts ineach group a are multiplied together by conductors a leading to tripleconductors L L L, which may be connected to the arms of one of asuitable number of switches S of the trunk selecting apparatusE, thesebeing best shown in Fig. 3. The trunk selecting switches are of the samecharacter as those of the office Selectors having revoluble con tactarms .9 5- s to which the main c0n.- ductors L? L and the thirdconductor L may be connected. The arms are mounted upon a shaftsanddriven by a single motor magnet M, with a retaining magnet H bothprovided with armatures and pawls acting upon a ratchet Wheel 8 ThisWheeloperates, an off normal contact device 8 There are three sets offixed contacts 8 over which the arms are moved. The connection of thecontacts of the arm 3 is local to the apparatus Pl, being. for testpurposes as will later appear, but the contacts of the arms 5" and s areunited to trunk conductors Lf and L, respectively, which lead to thedistant office to, which the section of the associated oiticc selectingapparatus D corresponds. These trunks are arranged in groups of amagnitude suiiicient to satisfy traffic conditions, and similar contactsthroughout the groups of switches S are multiplied to the trunks bymeans of pairs of conductors '0 (Fig. 1), so that any switch may haveaccess to any one of the trunks. It will be seen, therefore, that underthe influence of some appropriate controlling means, each apparatus Dmay first pick out a group of selecting apparatus E represent ing aparticular oliice and then an idle trunk selector, which in turn mayseal; an idle trunk couple terminating in such distant office. In. doingthis the switch S of the iapparatus D is required to move its con tactar is to the proper section a of the fined Etcrmina s, (2) advance saidarms until they reach contacts 5 connected to nonousytrunk selectingapparatus E, and (3) sto the argms and establish the circuit throughthetnunk selector. To vary the circuit connections. for. theaccomplishmentof this, each. apparatus ll). includes three relays it 31and It, the relay R having two windings. he first when energized putsthe ap paratus. in condition for operation; condition (1) follows withl1 energized and B1 deenergizcd; for condition (2) R and R are bothei-iergized, and, finally, for condition (3), R 1s decnergized and l t-QHQIw gized. The trunk selecting apparatus E has only to advance itscontact arms to an. idle trunk, and. to aid in this a single relay E. isprovided. In addition the motor magnets Mi and M. and the retainingmagnets H and H have other armatures than those actuatingv the pawls,these sharing in the control of the circuit.

Linecelecing appomzua.-Fron the fixed terminals, with which the arms a sof each trunk selecting switch cooperate, the two -i':onductor trunks LiL extend to apparatus for selecting and connecting with the called line,which may, of course, belong either to the originating or to a distantoilice. In either case at their incoming ends each pair of trunkconductors is equipped with an apparatus h (l ig', for furnish ing enery to this portion of the circuit and for controlling the-connection.This includes a repeating coil f, having one winding bridged across thetrunk and the other winding" joined to conductors 1 and l f which leadthrough relay contacts to the conductors L and L and extend the talkingcircuit. Condensers f f are inserted between the sections of eachwinding of the R and R each have two windings, which in the relay It areof relatively high and low resistance, said windings being designated bythe characters 1 and r respcct-ively. The functions of these relays andalso those forming a part of the line selecting apparatus will be betterunderstood after themechanism composing said selectin; apparatus havebeen enumerated.

It bcing'rememl'iered that ten-thousandline. oillces were assumed, thecalled line may group i leads or conductors L be conveniently arrived atby passing through three successive sections of apparatus: the firstselecting the thousands in which said line is. located, the second thehundreds or an allied group and the third the tens group and theparticular unit therein. These three assemblages of apparatus may betermed, respectively, the primary selectors I, the secondary selectors Iand the final selectors or connectors 1 To the conductors' L and L ofeach trunkis permanently assigned a primary selecting apparatus whichalso has a thirdconductor L connecting it to the apparatus F. Thisprimary apparatus 1 may be much the same as the oliice selectingapparatus D, the shaft 8 of its switch S carrying main contact arms 8and s and a test arm 8, movable in long and short steps over terminals.9 by

successively acting ratchet mechanisms under the influence of motormagnets M and M and temporarily tionto which it is driven, by detentmechanism associated with a retaining magnet H. An ofi normal contactdevice a, double wound relay R and a marginal relay R and relay contactsupon the motor magnet M and retaining magnet H are features of theprimary selector. The same general considerations of machine and trunkefliciency and economy obtain throughout the line selecting apparatus asin the office selectors, and it. may be that it is foundexpedient-,'-for example, to employ selecting switcheshaving in all 200fixed terminals.

Itwill be assumed that such are to be used. In the primary switchesthese terminals are divided into ten groups to (Fig. 2) corresponding;to the thousands of the total numbeitfof lines in the ofiice, each ofwhich groups may include twenty terminals. Similar terminals of eachgroup in all the primary' selectors are multiplied by conductors to, tointer-apparatus trunks having main L and a third conductorL (Fig. 4).Each of the conductors U terminates in a contact device of secondaryselecting apparatus 1, while leads L and L extend to the contact arms s862, respectively, of switches S belonging to said secondary selectingapparatus. This enables onset the primary selectors to appropriate forthe continuation of the connection the first idle secondary selector.The motor magnets M and M retaining magnet H h voii normal contact a andrelays R and-R the'latter being marginal, are hereasin theprimaryselecting apparatus.

The fixed terminals 8 of the switches S? are'divided into'secondary orhundreds groups (Figf 2),,isomewhat as are those sands groups, and'foijsimilain reasons are multiplied by coaducttrsa a; trunk con} '1leadin held at the posifinal selectors I, but as already pointed out,the switches are of two hundred points each,

so that the secondary groups will comprise two hundred instead of onehundred units, and there will be five of such groups to each thousandand five sections containing forty contacts 8' in the switches S Thefinal selectors I have connecting switches S to the main arms a s ofwhich the trunk conductors from the second ary selectors may be tensionsL and L the test arm 3" is local to the apparatus 1 The fixed term'inalss of these switches H are in twenty sections y (Fig. 2), representingthe tens of the-full group of two hunis joined through ex Theconnectionof dred; each section having ten unit terminals to which thesubstation lines, one of which is shown at Z, Z", with thetbirdconductor to the answering jack J are multiplie by conductors 1 ,1 and Zas shown in Figs. 3 and 5 but indicated collectively at y in Figs. 1 and2. Connected i with this substation line are its line and cut; oilrelays R and R and a line lamp O. motor magnet M in this switch movesthe contact arms in long steps from one tens section to another, whilemotor magnet M carries them by short steps over successive unitterminalsuntil the line sought is reached. A retaining magnet H acts in the usualmanner. Having in mind of the three kinds of line selecting switches,the functions of the relays at the incoming curl of the trunk andincluded in the primary and secondary apparatus may be stated. Relay R?assists in controlling the supervisory signal 0 The remaining trunkrelays affect three groups of results-first, to establish and maintainconnection between battery and the conductor L this renderingpossiblethe succeeding operations of the primary selector, it appliescurrent to the retaining magnet. H of said primary selector, which inturn does the same for one winding of the primary selector relay thepurpose and relation R, then to the test arm 8 and relay R; I second, toreceive and repeat locally into i the line selecting apparatus impulsestransmitted from the calling oiiit i; third, to establish the talkingcircuit. These are brought about as follows: First, relay R momentarilyestablishes the desired connection with conductor L, which is thentemporarily retained byrelay P tand ultimately relay R second, relay Rreceives and repeats into motor magnet-s M M and M of the primary,secondary and iinal selecting switches, respectively, the series ofimpulses which correspond to .the

thousands, two-hundreds, and hundreds and tens of the,desiredl number;relay R receives and} repeats into relays it and R and motor magnet M ofthe final selector arcane? the two single pulses and one series ofpulses which are sent out from the calling" ofice to start the primaryand secondary selector arms seeking for non-busy inter-apparatus trunksand to move the final selector arms to the unit terminals of the desirednumber; third, as soon as all the selectin impulses have been receivedand the talking circuit is established in thecord by the deenerg'iaationof relay it, relay R is energized. This relay JR shunts itself by relayR, which in turn energizes relay R. The lastsramed relay establishes thetalking circuit, maintains the'circuit of relay it, opens the circuitsof relays R and R, and substitutes a direct connection between theconductorl} and battery for the previous connection through the windingof relay R The ends attained by the relays of the primary and secondaryselectors are closely analogous to those accomplished by the relays ofthe oflice selecting apparatus D. That is, in the primary selector 1, tocause the arms of the switch S under the in flue-cc of the callingoiiicc to (1) seek the section 10 of its contacts from which conductorslead to the multiplied secondary selectors l representing the thousandof the called line; (2) to continue the movement by shorter steps withinsaid section to reach an idle trunk, and (3) to stop the arms and Therelays of the complete connection. secondary apparatus l eflect the sameresult with respect to the finalselecting ap-' paratus l. The operationsfollow one another in the order given with (1) relays R and R ener'ized. and R and R deenergized; (2) R R" and R R all energized, and '(3)with It and R deenergized and R and l energlzed.

Returning now to the final selector, all: the apparatus of this class atthe oli'ice would have associated with it a ringing" generator N and abusy signal mechanism N Each final selecting apparatus has as signed toit a group of relays. fOt these, negatively polarized relay E by meansof a final impulse of current from the calling oiiice, closes thecircuit of the test arm a,

and of the busy signal mechanism; double wound sluggish relay R isadapted to control the display of a busy signal to the oporator; R,which be termed the primary connecting relay, completes one side of theline, cuts oil the busy signal mechanism and closes the circuit of therelay R relays R and it, the latter having two' windings, apply ringingcurrent to the called line, and relay R the secondary connecting relay,interrupts the ringing current and completes the talking circuit. Invarying the circuit connections, relay con-. tacts upon the retainingmagnet H and of normal contact devices a and a assist.

'ao aratus.

til"

the oflice, trunk and primary and secondary line selectors for an idleapparatus among the multiple of the succeeding class to which it hasaccess takes place under the control of the previously mentioned relayswithout the direct intervention of an operator. The selection of the,ofi'ice at which the called subscribers line terminates and of all thegrou s of units making up the number by whic 1 said called subscriber isdesignated is under the control of the calling subscribcrs operator,therefore, to start the series of selective operatipns and to governthem, each operator is provided with a controlling apparatus T (Figs. 6,7 and 8) which receives current from the ofllce battery through a mainlead L Said current, in certain of the controlling circuits, isinterrupted to furnish motive impulses by one or more pulsators of anyconvenient type. Like the battery, these pulsators have been shown inthe drawings in a number of places and indicated by different charactersof reference for convenience in description.

With such an exchange as that now under consideration the contypllingapparatus,

which is shown as connected with the apparatus of the cord circuit C byconductors L L and if, and with the office selector 1) by a conductorif, may have'three sections T and '1, corresponding, respectively, tothe offices of the exchange, the

thousands and hundreds digits of the total numberof subscribers, tenthousand, which 'may be connected to each, and the tens and.

units digits of said number. Each section is provided with a set of keysequaling in lnumber the offices or digits, the selection of which itgoverns, there being ten office keys K in section T ten thousands keysl' and ten hundreds keys K in sectio1i."i and ten tens keys K on" tenunits keys K in section 1, each being preferably designated in practiceby the office or digit which it represents. The keys may be of anyconvenient form, and are each provided with twocontacts normally openbut closed upon the depression of a key. Each set of keys has a lockingmember I; to maintain a depressed key in this position until released bythe cnergization of an electro-magnet 72 Combined with each set of keysis one or more electromechanical switches, preferably organized in thesame general way as those of the selecting apparatus, and these will behereinafter referred to without describing" them in detail. Groups ofrelays are also associated with each set of keys and those will be moreparticularly mentioned and their functions stated after an enumerationof the major mechanisms of the controlling o affect the oilice selectingapparatus D y 1 1n accordance wlth the condition registered upon thekeys K at the controlling appanew 'ratus, said keys (Fig. 6) areconnected consecutively to one of ten fixed cpntacts-s of a sendingsw1tchS which governs the number of selective impulses applied tothefactthat although the primary groups of the line. selecting apparatusare arranged by tens, that is, upon the decimal system, as naturallywould also-bethe digit keys before the operators, the secondary groupsin the thousands will all be of two hundred units each and thereforenon-decimal. To

' cause the 'decimally designated keys to conmagnet M is connectedconsecutively to a A control the sending of selective impulsesd redskey. 1 The contact a trol selection non-decimally it becomes necessaryto in some way change or translate the condition originated into adifferent condition actually transmitted. For this purpose the combinedthousands and hundreds sect-ion is equipped both as a controlling and atranslating apparatus. It has a switch mechanism S (Fig. 7) the shaft ofwhich supports three contact arms 8 si 'and s revoluble in lon and shortsteps by motor magnets M and I, respectively, and temporarily held by aretaining magnet Each arm cooperates with a set of fixe d contactsdesignated, respectively, by the characters 8 8 and 8?, there being .100in each set,and thus equalingthe possible combinations of ten thousandskeys with ten hundreds keys. Every tenth point 8 of the set 8, or thoseseparated by intervals equivalent to the long steps of the s rin of athousands ke. K and serves to to the primary apparatus I. Theintermediate points are spaced from one another in accordance. with theshort steps produced by magnet M every tenth point being multipledtogether in sets of ten and connected to a spring in the correspondinghunultimately reached by the arm 8" determines the point at which thearms s and 8 shall. rest upon the contacts 8" and s and it ma beconsidered that upon these the original numeri- I cal conditioninitiated by the hundreds keys .being primary ands auxiliary. It is nowdesired to transmit impulses to the secondis registered. For this-reasonthese will hercun fter be termed register contacts, 8"

ary selectors 1 according to their non-decimal arrangement of fivetwo-hundreds groups to the thousand. For this purpose the contacts 8 ofthe primary register are connected in pairs, thus giving the fivegroupsin each of the ten thousands which the entire hundred contactsrepresent.

Then, as the only function of this portion magnet M and a retainingmagnet H I'fthe' number sought fell within the first hundred of thetwo-hundred group, it would only be necessary to proceed with selectiontherein through the final connecting apparatus by tens and units. If,however, it is in 'be advanced over the first hundred before saidselection begins. To accomplish this the first and every alternatecontact 3 of the'auxiliary register is multipled to a conductor leadingto relay mechanism which puts the controlling section '11 into action.The second. contact 8 and every other alternate point is similarlymultipled and is joined to relay mechanism'to bring into play anauxiliarysending switch s,'the motor magnet M of which causes its arm 5to take 'ten steps, and ten impulses to be transmitted to the motormagnet M of the connector I carrying it by tens over the firsthundred'of its two hundred contacts. At the termination of its tensteps, during which the arm'is temporarily held 'under the influence ofa retaining magnet H the arm 5 rests upon an active contact 8 completinga circuit which transfers the control to the tens and units section T".-l

The section T (Fig. 8) includes a combined tens and units sending switchS of which the arm 8 first travels from one tens contact 5 to anotherunder the in fluence of a motor magnet M and then is moved from unitscontact 8 to units contact by motor magnet M To govern these movementsand the impulses 'sent to is operating or idle. The remaining relayshave three functions (1) to close a motor magnet circuit, (2) to opensaid circuit: when l the deslred impulses have been transmitted,

the second hundred the connector arms must- Ofthe relays of thecontroller Twhich hundreds sending switch S This switch is provided witha contact arm 8 a motor the connector each tens point is joined to atery lead will show whether the contrbller flee to be brought intocircuit, instead the second relay R disconnects the controller from thecord. in addition'to What have been mentioned, the controller hasofi'ice test relays R and R, a thousands test relay R and a hundredstest relay R Of the controller relays those numbered R R R R R R R and Rare sluggish, while relays R R R R and R have each two windings.

Operation of the system.

To show the operation of the system, the

manner of receiving a call will now be described, together with thecompletion of the desired connection with an idle line and the failureto so connect with a busy line; at the same time the circuits involvedwill be traced. It may be assumed that the subscriber at substation a,which has an answering jack and its signal at central station A, wishesto communicate with subscriber at 06 whose line belongs to centralstation A and whose number is 2132. The subscriber at substation a (Fig.3) takes the receiver from its hook, completing a circuit from battery Bthrough conductor 14, one winding of relay 1t, armature 11 and its backcontact in cutoil' relay conductor 12, limb Z of the line, substationset a, limb Z of the line, back contact and armature 13 of relay Il andsecond winding of relay R to ground. Thisci'iergizes the line relay,thereby closing a local circuit 141 including armature 1 1, battery 13and the line signal lamp 0, which is thus illuminated. In response tothe signal, the operator before whom it is situated inserts the plug Pof one of the cords G at her position in the answering jack J of thecalling subscriber-"s line. This results in the energization oi. thecutoff relay R, originating relay i and supervisory relay R by thesimultaneous clos ng of two circuits, one from battery B to g1 oundthrough the winding of the cutoli' relay, conductors Z and L and windingof relay It; the other from the negative pole of battery B, one winding15 of the repeating coil 0, winding of supervisory relay 1 limb Z of thesubscribers line, substation set, limb Z of the line, and winding 16 oi?the repeat ng coil. 'lhe energization of relay selector 1), conductorsIt disconnects relay It froni the subscribers line, resulting in thefalling back of the armature 1st and the extinguishing the line lamp 0.The operation oi relay it", through its arn'iature 1-0 and its frontcontact, places battery B' on conductors 17 and 18 and lightssupervisory lamp 0 which is connected to ground. The energization ofrelay R opens the contact of its armature 19 and prevents the lightingof the supervisory lamp The operator throws the key K in the cordemployed into the listening position and connects her telephone athrough the springs 20 20 with the talking strands U L of said cord,and'at the same time closes at the springs 21 21 of the key a circuitfrom the battery B (Fig. 8), through spring 22 of the controllerconnecting relay R conductor L, normally closed springs 52 52 of thecontact device a of the office 3 and 23, back contact and armature 24 of,cord relay It, winding of connecting relay R conductor L winding ofrelay R conductor 25 and back contact and armature 26 of units relay On.operating the relay R by its armature 22 disconnects battery B from theconductor L and connects it to the main battery lead L, which with itsbranches is shown in heavy broken lines so that it may be readilydistinguished, and to thus avoid the necessity for tracing back to thebattery 13 the many circuits of the controller. When battery isconnected to this lead hold-- ing magnets H of the o-fiice switch S H ofthe thousands-hundreds switch S 1 of sending switch 8" and H of the tensunits switch S are energized by current to ground. The path of the firstis through conductor 27, armature 28 and its back contact in relay R andconductor 29; the second through otl' normal contact 8" of switch S andconductors 30 and 31; the third through spring 31 of relay It andconductor. 32, and the last by ofi' normal contact r of switch S andconductors 33 and 3t. At thesamc time the lamp is illuminated and socontinues while the controller isin operation. The armature 35 ofcontroller relay R closes contact with spring 36 before breaking theresting contact of the spring, with the result that by means ofconductors 38, 39,- 4:0 and :41 the key releasing magnets Z1 of all thecontrolh-u sections are momentarilv energized by current from battery llf The object of this is to free any key which mighthave beenaccidentally depressed before the operator is ready to register thedesired number.

The operation of controller connecting relay R 'in the cord, which wasenergized simultaneously with the starter relay 1t, disconnects by itsarmatures 76 and 84: the talkiiig leads Lf L of theofiice selector Drelay by the operatidn of keyjK but which is oplened by th"8nrg1Zi}blOI1 of relay tion the other armature 48 of R. cpmpletes acircuit from battery B to from the cord strands L L and joins theformerto the controlling apparatus through conductors Ligand L. Armature.42"of relay R closes a by-path by mr ductor through one winding ofcordrelay R ,conductor 44, contact of. key'jK, conductor '18 and frontcontact and armature 16 01. R?- to battery 3*". This by-path' serves"the double pur'pose of energizing the guns zany R 4 and substitutin' a;path to attei'y for the circuit of relays Ff" and R in place "6f that tobattery B through armature Qeibf relay R, which circuit was closed nowR.

is prevents any subs'e'quent throwing of the key intothe listeningposition from interferiiig with the circuits, and the attracthis relayfiroundthrough the armature 16 of relay complete p n of the limit of,iconductor18,contact45 of key K, secondj winding of relay R, conductorL and windingof' oiiice selector relay It. This energizes" relay R andlocks relayi-R making'git independent of the circuit established throughits first-mentioned windin ()n'operati ng th ejrelayR clo'sest e frontcontacts of its three armatures 49, and 51. Armature -eiil'connectsground to the winding of relay It! Armature 50 prevents the "ductors'Land L, which would otherwise take place upon the separation ofithesprings 35;

52 and 52 of the-0d normal device a, when thefinotor hin'agnet of theoilioe selector ref'sp'onds'to'ithe impulses which it is to re- "ceive,Armature 51 closes a circuit through conductorf53 from ground to batteryB 'thioughthe winding of retaining magnet H Then the office selectorrelay R is ehergizeil by "current in one winding from -batt'ery B toground through the armature 5'4 and its front contact in the retainingmagnet H conductors 55 and 56, spring 57 audits restin condiictor 58. i1

contact'in relay R and 'W disconnects its armatures 59, 60 and 61 fromthe arms '8' s and 8 of the office selecting switch and closes theirfront contacts. The

apparatus is now rea y for automatic select1on'to begin whent; eoperator has reg stered the office and. number upon the con-jtroller'keys. 1 v

The selection of the oficaand' a trunk leading th ercta- -Ip accordancewith the number A -2132, th

of the ofiice sending switch S tothe main and'63 of the key'anddonductor 64, and also closes a the pantr lead through en energizedthe relay R? e operator depresses j the qlficekey' AFuKiQQt'houSjathdskey 2K, hundedskey lKf-"fl tensfliey 3K. and units" key 21 The'depression of the olfice key connects "the "second lfixed contact point8 ccnductor 62, key spring s63, 63 and c5,

conductors 66 and 67, winding of relay R and itsjspring 68 to anintermittent ground provided by pulsator P Since the puleater is inconstant motion relay 1t will be energized at a time substantiallycoincident with the depression of the oflice key; On operating thisrelay locks itself to ground by its armature 69, disconnects itself fromthe intermittent ground of the pulsator, and closes the following pathfrom the spring of the pulsator P which is connected to battery B toground; armature 7 O, conductor 71, winding of motor magnet M backcontact and armature 7 2 of relay R conductor 73, back contact andarmature 74 of relay R3 conductors 75 and L, armature-7 6 and spring 76of relay R talking lead L armature 59. and its front contact in relay R,conductor 77, winding of motor magnet M, conductor 77 a and spring 78 ofrelay R Since this circuit contains the windings of t wo motor magnets,either of which may be more sensitive, it is essential that the firstpulse of current over the circuit-when it is closed by the operation ofthe controller relay R shall be complete and not fractional. This isaccomplished by including in the initial circuit of the relay R theintermittent ground contact of the pulsator P, as has beenalreadydescribed, thus fully energizing it before the pulsator applies currentto the motor magnets. Said mag' nets M and M'- now will drive forwardsimultaneously the contact arms of the oflice controller switch S andthe selector switch S, the latter covering a section a at each step.When two pulses have been transmitted through the motor magnets the armof the controlling switch will close 1 a path from the batterylead L toground throu h conductor 62, springs-63 63 ofthe pressed key, conductor64, switch armis conductor 79 and one winding of relay R This relay thenoperates. and breaksthe circuit of magnets M and M at itsarmature .7

72. The arms of the oflice selectorare now at rest on the first tripleset of contacts of its second section. If the .trunk selectorEconnectcd'with this set of contacts is not busy it is only necessary torelease'relay R; if the trunk selector is busy the movement of the armsmust be continue'd'until they are brought to rest'on contacts leading toa non-busy apparatus. 3

It will be noted that the previously. de-

scribed path through the winding of relay RS is only one of twowhich'run from'conductor 79 to ground. The other path consists ofconductor 80, off normal contact dewice a, which is now closed,conductor 81,

back contact and armature 82 of relay R, conductors 83 and L, armature84 and spring 84 of relay R, talking-;leadlf*,,

armature 60 and its front 'oontacti' inrelay" R conductor 85, winding ofrelay R and front contact and armature 49 of realy R Therefore, relay Rof the office selector was energized simultaneously with relay R of thecontroller when the contact arm of the office sending switch reached itssecond point. On operating the armature 78 of relay l 22 disconnectsground from the motor magnet M and closes from ground to armature 61 ofrelay R, which armature is joined to the test arm 8 of the officeselecting switch, a multiple circuit consisting of (1) conductors 86 and87, one winding of relay R and conductors 90 and 88, and (2) ls'conductor 86, the winding of the motor amagnet M its armature 89 andconductors 90 and 88. The operationcf the armature 91 of relay R opensthe circuit of the winding of relay R connected to conductor 58, andlocks relay R to the battery 13 by means of spring 57, conductors 56 andand armature 54 of retaining magnet H and its front contact. If thetrunk selector with the leads of which the arms of the office selectorare now in contact is busy, conductor L will be connected with thebattery B of th'e office selector already associated with it. Therefore,although the circuit of one winding is open, relay R will bekeptenergized by current passing from conductor L through the test arm 8of the office selector, conductor 95, armature Gland its front. contact,conductors 88 and 90, second winding of relay conductors 87 and 86 andarmature 78 and spring 78 of relay R, which is now energized. CurrentWill also flow through the other branch of this circuit which includesthe winding of motor magnet M and hence the contact arm will be drivenforward until the test arm comes to rest on a lead which is notconnected to battery, that is, until a non-busy trunk se lector isattained. Then, since current no longer flows through either winding ofrelay R it is denergized, breaks at its front contacts all its circuitspreviously described, connects talking leads L L through the two upperarms to the talking leads L L and unites battery B to conductor L bymeans of the test arm. This readers the chosen trunk selector busy, toguard, as has just been outlined, against its appropriation by anotheroffice selector. When this occurs current will flow from the conductor Lto ground by three paths: (1) through spring 96 of the 0H normal device8, conductor 0/ and the winding of the retaining magnet H (2) springs 96and 98, conductor 99, back contact and armature 100 of motor magnet Maird winding of said magnet, and springs 90 and 98,. conductor 00 andthe winding of relay R The magnet H applies the retention pawl, and byits armature 101 closes a path through conductor 102 to conductor L,which makes the cir- 'cuit for the retaining magnet independentarmatures 103 and 104, and connects at armature 104 the test arm a toconductor 99 through conductor 105. The'motor magnet M in response -tothe current flowing through its winding, propels the arms from theirnormal position and opens contact springs 96 and 98. Although theopening at these springs disconnects condiictor L from relay R andmagnet M, these will be supplied with current by means of the test armfrom the battery B of an office selector associated with a busy trunkselector through the multiple of the test contacts, until said test armand the main-contact arms come upon the terminals of a nonbusy trunk,then current no longer being found atthe test contact, relay R will bereleased, thereby re'r'stablishing the connection between the arms .9and s and the talking leads L and L atthe armatures 103 and 104,disconnecting the test arm from conductor 105 and joining it toconductor L by conductor 106.. The conductor L being connected tobattery B, the test arm establishes on the test terminal correspondingto the selected trunk the condition which will prevent its being takenby some other trunk selector. v v

The selection of the thousand g1'0up.'Returning to the considerationofitlie controlling apparatus, relay R when energized not only openedthe contact of armature T2 to stop the advance over the'sections u ofthe office selector arms, but also closed a circuit from ground to themain battery lead L through its second winding and the winding of relayR by way of the conductors 107 'and -108. This latter relay is designedto operate sluggishly, in order that its armature 82 will not open theback contact before office selctor relay R has had time to lock up. Uponoperating the armature 74 of relay R opens its back and closes its frontcontact. l\'o further action occurs in the controlling apparatus untilthe office, selector has completed the finding of a nonbusy trunkselector, and subsequently the latter of a non-busy trunk. But whentrunk selector relay R is det nergized and the connection between thelead L and arm 8 is reestablished, current flows from the battery lead Lthrough conductors 27 and 109, spring 110 of relay R conductor 111,winding of relay R, conductor 112, front contact and armature 74E ofrelay R i conductors T and L, armature 76 and spring 76 of rblay It,talking lead L armature 50 and its back contact in relay R officeselector arm .9, talking lead L, armature 103 and its back tontact inrelay 13"", trunk selector arm a, talking lead L of the interoificetrunk, conductor 112, spring 113 of relay R conductor 114, winding ofrelay R, conductor 115, back contact and armature 116 of relay R,conductor 117, back contact and armature 118 of relay It, conductor119,"spring 120 of relay It, talking lead L armature 140 and its backcontact in rela R and primary selector arms a to groun at its restingcontact. Controller relay R and trunk relay R are both energized by theclosing of this circuit." The armature122 of relay R are both energizedby the closing of this circuit. The armature lished by relay R byconnecting its winding to the battery B, through the conductor 130 and.spring 131 ofrelay R. The arma-- ture 132' of relav R substitutes itscontact with the spring 113 for the resting contact thereof, but thishas no effect until relay R is deenergized and its armature 122 assumesits normal position. Armature 133 of bold ing magnet H ,'by closing atits front con-- tact a connection between conductors 127 and 134,prevents the separation of conductors L and 127 when the oil normalcontact device s is opened upon the actuation of the switchS. Thearmature 135 closes a path from battery B to ground through conduc-1vtors 136 and 193, spring 137 of, relay R", conductor 138 and onewlnding of relay R.

The functions of this relay are analogous to those of the oific'eselector relay R. It

' temporarilydisconnects leads L L from arms-8 and s and closes thefront'contact s of its armatures 139 140 and 141; Considering again thecontroller relay R, which was energized simultaneously with the trunkrelay R, itsarmature 142 closes the circuitofrelay R from the batterylead L through conductors 27 143 a and 144. This relay R by means of itsarmature 145 looks its winding to battery by way of'con-- ductors 27 and1 09 andspringllO, and opens the resting contact of said spring-andthe.-

energizing, circuit of relays R and R, thereby releasing them. 'Thearmature 28 of-relay R opens-at its back contact the circuit of theretaining magnet H of the ofiice sending switch S, the arm a of which isreturned by its spring. to its initial position. Uponits front contactthe arma-- 'ture 28 closes a path from'the main battery lead throughconductors 27 and 146, armature 147 and its back contact in relay R andconductor 148 to the springs 149 of the thousands keys K Since the keyof the digit 2 is depressed, current will flow on.

from conductor 148 through springs 150 and 151, conductor 152, windingof relay R and its spring 153 and conductor 154 to an intermittentground at pulsator P. Then relay R attracts its armatures, locks itselfto a permanent ground connected to the armature 155, opens the-contactleading to the pulsator, and closes the front contacts of its armature156 and 157. There is now a closed circuit from the pulsator through thewinding of motor magnet M conductor 158, front contact and armature 156of relay R, conductor 159, back contact and armature 160 of relay R,conductors 161 and L, armature 76 and spring 76 of relay R which isstillenergized, lead-L, armature 59 and its back contact in relay R arm 8 ofthe oflice selector,-lead L armature 103 of relay R a'i'm s of the trunkselector, lead L, conductor 112,

spring 113 and armature 132 of relay R conductor 162, back contact andarmature 122 of relay R, conductor 163, winding of relay R conductors164 and 115, back contact and armature'116 of relay. R, conduc-v tor117, back contact and armature 118 of relay R conductor 119, spring 120of. relay R, lead L armature 140 and its frtnt contact in relay R,conductor 165, and

spring 166 and winding of relay R to ground. The closing of the circuitallows pulsator P 'to send a series of impulses through the motor magnetM the relay B of the trunk and relay R of the ,primary selector. Relay Rbeing marginal will not be energized by the series of pulses. passingthrough it, on account of the high resistance of relay R and motormagnet M The first pulse which passes through the motor magnet drivesthe arms of the thousands hundreds switch 8 from, their normal positionto the zero member of'the doiiperating set of fixedgcontacts; the secondpulse will drive the arms from the zero contact to the first tenscontact .9? while the third willadvance them to the second tens contact8".

As will appear shortly, not more than threev impulses will be sentthrough the circuit under consideration. 1 At the same time, by meansoftrunk relay R*,the'following cirjcuit from battery B to ground throughthe. winding-of motor magnet M" of the primary selector will be closedthree times-er mature 1670f relay R, conductor 1168,

spring 169; of relay R, lead L, armature 139 and its front contact inrelay R condoctorv 170, winding of mag et M and spring-171' of relay RThus it will be seen t at the: three impulses which the pulsator Ptransmits through motor magnet M and relay R not only propel the arms ofthe thousands-hundreds switch, but, by,

contacts.

When the arm .9 of the thousands-hun dreds switch S comes in contactwith the twenty first point 8 or that corresponding to the numeral 20,current will flow from iead L to conductor 148, as previously traced,through springs 149 and 150 of the epressed thousands key K conductor172, 1 a, conductor 173, armature 174 and back contact in relay R andconductor to ground through two pathsone -ough COIlClIlC'JOI' 176 andone Winding of relay R thereby energizing it; the other throughconductor 177, armature 157 and its front contact in relay R conductor178, back contact and armature 179 of the relay R conductors 180 and L,armature 84 and spring 84 of relay R lead L armature 60 and its backcontact in relay R arm 8'? of the oflice selector, lead L armature 104and its back contactin the relay R arm 8 of the trunk selector, lead L,one Winding -181 of the repeating coil f, conductors 182 and 183, spring184 of relay R conductor 185, Winding of negatively polarized relay R,conductor 186 and Winding of positively polarized relay R energizing thelatter but not the former because the current floWs from the positivepole of the battery B The operation of the armature 160 of thecontroller relay R breaks the circuit containing the motor magnet M" andrelay R, and therefore the local circuit through the motor magnet M isalso interrupted. The armature 110 of relay R opens its back contact andcloses a circuit from battery 13 to ground through conductor 117, backcontact and armature 118 ofrelay R conductor 119, spring 120 of relay R,lead L armature 140 and its front contact in relay R conductor 165 andspring 166 and winding of relay R thereby energizing said relay. Thearmature 187 of relay R before breaking the resting contact of spring166, locks the relay to battery 13 through conductor 136and armature 135of retaining magnet H The armature 188 of relay R makes con tact Withits spring 137, Which at this time has no effect, and opens the restingcontact of said spring, thus breaking the circuit containing a Windingof relay R. The armature 18,9 of relay It opens the resting contact ofits spring 171, and therewith completes circuit from ground to the testarm 8 through armature 141 and its front contact in relay R and theparallel paths consisting of (1) conductors 190 191 and 192-with thesecond Winding of relay R,

and of (2) conductors 190 193 and 192 With the Winding of the motorenagnet M. In the same manner as described in connection WitlLthB ofiiceselector, the test arm 8 of the primary selector will retain relay Renergized and operate motor magnet M until the arms of the primaryselector come into contact With leads to a non-busy secondary selector 1then relay R is decnergized, armatures 139 and 140 connect leads L and Lto arms 8 and 8 and a circuit is closed from battery B to ground throughthe armature 135 of holding magnet 1. conductors 136 and 193, spring 137and armature 188 of relay R conductor 194, armature 141 and its backcontact in relay R test arm a, lead D 011 normal contact device .9conductors 195 and 196 and the Winding of the retaining magnet H Uponthe energization of this magnet its armature 197 closes a contactbetween conductors 195 and 198,'Which short 'circuits the OE normalcontact device. The armature 199 of magnet H" 'closes a path frombattery B to ground hrough conductors 200 and 201, spring 202 of relay Rconductor 203 and one Winding of relay R. Upon operating this relaydiscon nects its armatures 204 205 and 206 from the arms .9 a and 3respectively and closes it front contacts.

The translation and selection of the 7mmd'r'cds gr0'up.--In the previousreference to the energization of the controller relay R the opening ofthe contact by means of its armature 160 only Was considered. Itsarmature 207 completes a circuit from ground to the main battery lead Lthrough one of its windings, conductor 2.08 and Winding of relay It,which is designed to operate sluggi'shly in order that it will not openthe resting contact of its armature 174 be fore relay R of the trunk hadtime to start the series of operations at the primary selector, asalready described. The armature 147 of relay R, by opening its backcontact and closing the front, disconnects the conductor 146, Which withthe conductor 27 extends to the main battery lead from the thousandskeys, and connects it to the hundreds keys through conductor 209. Thehundreds rey 1K being depressed, current noW flows from conductor 209through springs 210, 211 and 212, conductor 213 and Winding of relay Rto ground. 7 This, by its armature 214. closes a circuit from ground topulsator P throughv the armature 215 and its back contact in relay Rconductors 216 and 217 and Winding of motor magnet M As soon as oneimpulse has been transmitted, and therefore the arms of the switch Shave moved one short step from the fixed contact 8 num bered 20, Wherethey had been carried under the influence of the long step motor magnetM current will flow from conductor 209 through springs 210 and 211of'the depressed hundreds key, conductors 218 and 219, the latter beingconnected to the point of the contacts a, numbered 21, arm-s conductor173 armature 1.74 and its front contact in re ay R conductor 220 andwinding of relay R to ground. Relay R then destroys the circuit of motormagnet M at its backcontact, and closes at its front contact a circuitfrom the main battery lead to ground and containing its second winding,conductor 221 and winding of relay R. The energization of relay It opensthe contact of armature .17 9,

' which is no longer required, and by its 103 and its back contact inrelay R arm a, lead L conductor 112, sprin 113 and armature 132 ofrelayR, con'uctor 162, back contact and armature 122 of relay. R conductor163, winding of relay R, conductors 164 and 115, back contact andarmature 116 of relay R, conductor 117, back contact and armature 118 ofre-.

lay R, conductor 119, spring 120 of relay R, lead L armature 140 and itsback contact in relay R arm a, lead L, armature 205 and its frontcontact in relay R conductor 225, spring 226 and winding of relay R toground. This circuit only energizes relay R of the controller, sincerelay R in the trunk, being positively polarized, will'not operate onflow of current from the negative pole of the battery, while relay It,bein marginal, cannot operate in series with t e high resistance ofrelays R? and R. On operating controller relay R" locks itself to groundthrough its armature 227, opens at its spring 223 the circuitWvhich hasjust been described, and closes by its armature 228 a circuit fromintermittent ground at 'pulsator P through conductors 229 and 230,spring 231 and winding of relay R to the battery lead I L 'Ifhis relay Rlocks itself ten perinanentground by its armature 232" and spring 231,disconnects itself from the intermittent ground at its spring, andcloses thefront contacts of, its armature 233 and 234. We now have apath from the pul-- sator P to ground through conductor 235,

I armature-233 and its front contact in relay'R conductor 236, windingof motor magnet M belonging to the sending switch 8", conductor. 237back contact and ar'ma ture v238 of; relay R conductor 239, lead L, andto ground at the seoondary'selector through the windings of relays B,and R "ac-5 bythe same course as that just traced in relay R, arm 8 tor247, back contact a the negatively describing the energization of relayR As before relay R will remain quiescent, but

this time relayR will be energized, as pulsator P transmits positivecurrent. Motor magnet M and relay R now operate simultaneously. The'former drives forward the arm 5 of the switch S while the latter closesa circuit from battery E3 to ground through its armature 167, conductor168, spring 169 of relay R, lead L armature 139 p of switch S,'lead I),armature 204 and its R conductor 240, winding of'motor magnet M of thesecondary selecting switch S and spring 241 of relay R and its backcontact in front contact in relay When one impulse has been transmittedby the pulsator P and the arms of switch S have reached the first set ofcontacts a of the first group as, or that corresponding to the firstfinal group of two hundred numhers, the arm 8 of the primary hundreds.

switch S closes a circuit fromthe 1 r h conductor 242,

sending main battery lead throu arm 8 of the thousandsundreds primaryregister of switch S, which it will be're-,

membered is resting upon its twenty-second point 8 (numbered- 21),conductors 243, 244 and 245, and then to ground by two paths, the otherthrough conductor 246, front contact and armature 234 of relay R 9",conducand armature 248 of relay R conductor L armature 84 and spring 84of relay It, lead B, armature 60 and its backcontact in relay R arm 8lead L armature 104 and its back contact in relay Rt", arm s lead L,onewinding 181 of the repeating coil f, conductors-182' and 183, spring184 of relay R conductor 185, winding of relay R conductor 186 andwinding of relay B. These two paths one one through a winding of relay Rergize simultaneously relay R of the controller and relay B: of thetrunk, but not polarized relay R. The armature 238 of relay R opens itsback' contact, thereby destroying the circuit from the pulsator P RelayR opens the back contact of its armature 116 and. closes acircuit frombattery B to ground through conductor 117, back contact and armature 118of relay R conductor 119, spring 120 of relay R, lead L armature 140 andits;

back contact in relay R arm .9 of switch 8, lead L armature 205 and itsfront contact of relay R conductor 225 and spring 226 and the winding ofrelay R When attracted the armature 249 of relay R locks the winding ofthe relay to bat-.

tery- B through cnnductor 200 and the armature 199 of the retainingmagnet H and also opens the resting contact of its,

spring 226. The armature 250 of the relay breaks the circuit 200, 201and 203, contain ing one winding of relay R and makes

